Have Node::document() return a reference instead of a pointer

Source/web/WebPasswordFormData.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 139 matching lines @@
 
 } // namespace
 
 WebPasswordFormData::WebPasswordFormData(const WebFormElement& webForm)
 {
     RefPtr<HTMLFormElement> form = webForm.operator PassRefPtr<HTMLFormElement>();
     PasswordFormFields fields;
     findPasswordFormFields(form.get(), &fields);
 
     // Get the document URL
-    KURL fullOrigin(ParsedURLString, form->document()->documentURI());
+    KURL fullOrigin(ParsedURLString, form->document().documentURI());
 
     // Calculate the canonical action URL
     String action = form->action();
     if (action.isNull())
         action = ""; // missing 'action' attribute implies current URL
-    KURL fullAction = form->document()->completeURL(action);
+    KURL fullAction = form->document().completeURL(action);
     if (!fullAction.isValid())
         return;
 
     // Determine the types of the password fields
     HTMLInputElement* password = 0;
     HTMLInputElement* oldPassword = 0;
     if (!locateSpecificPasswords(&fields, &password, &oldPassword))
         return;
 
     assemblePasswordFormResult(fullOrigin, fullAction,
                                fields.submit, fields.userName,
                                fields.alternateUserNames,
                                oldPassword, password, this);
 }
 
 } // namespace WebKit